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- Title
Comprehensive study of the macropore and mesopore size distributions in polymer monoliths using complementary physical characterization techniques and liquid chromatography.
- Authors
Wouters, Sam; Hauffman, Tom; Mittelmeijer‐Hazeleger, Marjo C.; Rothenberg, Gadi; Desmet, Gert; Baron, Gino V.; Eeltink, Sebastiaan
- Abstract
Poly(styrene- co-divinylbenzene) monolithic stationary phases with two different domain sizes were synthesized by a thermally initiated free-radical copolymerization in capillary columns. The morphology was investigated at the meso- and macroscopic level using complementary physical characterization techniques aiming at better understanding the effect of column structure on separation performance. Varying the porogenic solvent ratio yielded materials with a mode pore size of 200 nm and 1.5 μm, respectively. Subsequently, nano-liquid chromatography experiments were performed on 200 μm id × 200 mm columns using unretained markers, linking structure inhomogeneity to eddy dispersion. Although small-domain-size monoliths feature a relatively narrow macropore-size distribution, their homogeneity is compromised by the presence of a small number of large macropores, which induces a significant eddy-dispersion contribution to band broadening. The small-domain size monolith also has a relatively steep mass-transfer term, compared to a monolith containing larger globules and macropores. Structural inhomogeneity was also studied at the mesoscopic level using gas-adsorption techniques combined with the non-local-density-function-theory. This model allows to accurately determine the mesopore properties in the dry state. The styrene-based monolith with small domain size has a distinctive trimodal mesopore distribution with pores of 5, 15, and 25 nm, whereas the monolith with larger feature sizes only contains mesopores around 5 nm in size.
- Subjects
LIQUID chromatography; POLYMERS; MACROPORES (Catalysis); MESOPORES; MORPHOLOGY; ADSORPTION isotherms; COPOLYMERIZATION
- Publication
Journal of Separation Science, 2016, Vol 39, Issue 23, p4492
- ISSN
1615-9306
- Publication type
Article
- DOI
10.1002/jssc.201600896